1. Field of Invention
The present invention relates to the security of digitized information, and more particularly to the methods and devices for deterring the unauthorized duplication of digitized information.
2. Description of Prior Art
A fair amount of work has been done to ensure the protection of digitized information, such as computer software (e.g., U.S. Pat. Nos. 4,811,288 and 5,233,563), but these applications assumed that the user would never have a need to access the actual digitized information in normal use. These solutions were directed to prevent the user from obtaining a copy of the actual digital information.
But not as much seems to have been done to ensure the storage security of digitized information such as music and video. Digitized music, as exists on CD ROM, was designed to be accessed by the user""s equipment for conversion to analog which can then be amplified and listened to. No solution was incorporated into the specification of CD""s format because it was accepted that the digitized information would be available at some point during playback. The availability of CD-ROM drives in personal computers only made the security situation worse. This security oversight is most likely partly due to the limited existence of devices having the high density storage capacity, ease of use, ease of transportability, and the like that was necessary for such unauthorized copying to be convenient. By the time digital audio tape (DAT) and recordable CD (CD-R) had become available, the unsecured CD format was set. Video is still ahead of the piracy wave, but as better video compression software becomes available, convenient copies of digitized video is becoming more of a problem, too. What is needed is a means for storing and distributing digitized information without making the digital image of that information accessible in such a way that unauthorized copies can be made.
As high density storage devices become smaller and cheaper, the piracy of digitized information will increase. CD-ROM, with its inherently vulnerable data storage format, will be a risk to its stored information. As advances continue to be made in the area of high density data storage devices (e.g., lower costs and higher storage densities), more and more information such as music (as is presently stored on audio CD-ROM""s), books on tape, videos, movies and the like will be made available digitally. Furthermore, as internet commerce grows, more digitized analog information (e.g., audio and video) will be downloaded from the internet making it most vulnerable to piracy because when this type of data is initially made available in digitally copyable files, the risk of data piracy will be at its greatest. What is needed is a means for storing digitized information digitally without making a usable copy of that digitized information available.
The present invention is a digitized information storage device which comprises one or more Digital to Analog Converters (DAC""s). By incorporating Digital to Analog Converters on the chip or within the chip""s packaging (a hybrid device), digitized information being output is made available in an analog form only (although some portion of the stored information could still be made available in a digital format). As a result, successive copies of the outputted information will have to be created from an analog source and those successive copies will degrade. This degradation of the quality of the stored information would act as a deterrent to some forms of data piracy. This analog output, digitized information storage device can be digitally Read/Write (RW), digitally Write Only (WOM), or preprogrammed.
In the Read/Write case, an encryption key would be used to store the data into the device in encrypted form; in order to play back the information, the information would be read out and decompressed externally to the storage device (where more powerful and costly processing is available), and then the decompressed information would be written back into the storage device where it would be decrypted by the integral decryption logic from which the plain-text would be converted to analog for outputting without that plain-text being made available off the device. It will be obvious to one skilled in the art that the storage could be accomplished separately from the device (resulting in a decryption device comprising analog outputs), but it is more convenient to store the initial version of the information with the decryption key (which is inaccessible outside the device). In addition, when such decryption is combined with a compression/decompression mechanism, the only plain-text form of the information available is the analog version of the decrypted and decompressed data; one could obtain neither a compressed nor a decompressed copy of the data in non-encrypted form. As a result, if one hoped to pirate the data, he would not only have to redigitize it but he would have to recompress it as well.
The WOM version would essentially be a one time programmable ROM (OTP-ROM) with integral decryption and DAC""s; this version of the device would be desirable when the information is simply encrypted and need only be decrypted and converted to analog prior to outputting. This version would be useful for information which cannot be significantly compressed (e.g., because of loss of quality resulting from available compression techniques).
In the last case, uncompressed digitized information is inserted into the device at the time of manufacture either as a OTP-ROM or during semiconductor manufacture. That digitized information need never be made available outside the device, and as a result, the decryption mechanism can be omitted. In this case, the device can be thought of simply as a ROM with integral DAC""s.
It should be noted that the techniques described herein for incorporating decrypting means prior to the data being converted from digital form into analog form for output are applicable to a variety of data encryption means ranging from such simple mechanisms as a ROM Lookup Table or an XOR encryption through the U.S. Bureau of Standards DES encryption to a public key encryption such as PGP. Furthermore, as will be shown, the encryption can be synchronized to the compression used, if any. In this way the data can be decompressed prior to decryption (the reverse of what is currently available) such that powerful computing means can be used for decompression which would give the user access to the decompressed digital information, but which, because it is still encrypted, would not give the user a usable digital copy.
While other solutions might place the decryption or other security means in a playback unit, this is inconvenient because it makes it impractical to use that information (playback) on other than that specific playback unit (or units if they are configured identically). The present invention has the advantage that, by placing the means to prevent unauthorized duplication within the packaging which contains the information, instead of placing that means all or in part within the playback unit, it is much more convenient to use the present invention. Also, in the case of factory programmed devices, devices can be made without the need for any information from the end user.
The present invention converts digitized information to a non-digital form prior to making that information available outside the device. Any information which is used in other than a pure digital form could benefit from the present invention.